Bug 462675

Summary:	Dolphin becomes unusably slow while a file transfer is in progress
Product:	[Applications] dolphin	Reporter:	Riccardo Robecchi <sephiroth_pk>
Component:	general	Assignee:	Dolphin Bug Assignee <dolphin-bugs-null>
Status:	CONFIRMED ---
Severity:	normal	CC:	fanzhuyifan, kfm-devel, softexpert, steve_v
Priority:	NOR
Version First Reported In:	24.08.3
Target Milestone:	---
Platform:	Neon
OS:	Linux
See Also:	https://bugs.kde.org/show_bug.cgi?id=454722
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Riccardo Robecchi 2022-12-05 15:44:18 UTC

SUMMARY
Moving files with Dolphin makes it unbearably slow, so much so that it stops responding to commands. This is true independently of the source and destination: I have tried transferring files both locally (e.g. from SD card to internal SSD, or from SSD to SSD) and on the network (to an NFS share) and the result is the same. Dolphin just becomes really sluggish, even in doing basic things such as scrolling up and down the list of files.
This behaviour wasn't present in 22.04, though I cannot say whether it was introduced with a Frameworks update or with the 22.08 version.

STEPS TO REPRODUCE
1. Transfer files (e.g. cut-and-paste)

OBSERVED RESULT
Dolphin becomes incredibly slow.

EXPECTED RESULT
Dolphin keeps on behaving normally.

SOFTWARE/OS VERSIONS
Linux: KDE neon
KDE Plasma Version: 5.26.3
KDE Frameworks Version: 5.100.0
Qt Version: 5.15.7

ADDITIONAL INFORMATION

Comment 1 Riccardo Robecchi 2022-12-08 09:59:59 UTC

Small update. After updating to Plasma 5.26.4, Dolphin freezes entirely until the transfer is complete. There's also no notification of the ongoing transfer, it appears once it's done.

Comment 2 SoftExpert 2023-10-18 06:23:04 UTC

I would reference also the bug #454722 - Dolphin becomes frozen if nfs shares declared in fstab are not available - previously the mount point was just showing empty. Currently reproduced with Dolphin 23.08.2.

Comment 3 Steve Vialle 2024-12-16 09:34:44 UTC

Marking confirmed and bumping version, as I can still trivially reproduce this behaviour in recent (24.08.3) builds, with a fast (~1000MiB/s) NFS mount, a slow (~130MiB/s) mechanical drive, and a garden-variety SD card.
Any operation that saturates I/O on a device, causes a drive to spin up, or touches a high-latency filesystem of any kind causes dolphins UI to freeze. i.e. perfectly ordinary usage rendering the UI borderline unusable.

There are countless related bug reports on the tracker, and for some reason https://bugs.kde.org/show_bug.cgi?id=423187 appears to be the only one receiving any attention whatsoever... Despite being 4 years old and initially specific to network mounts.
It's all the same problem though: IOPS are finite, filesystem latency is variable, and interactive UI threads shouldn't be blocking on I/O... *especially* I/O initiated by simply using the file-manager for its intended purpose. That's a horrible UX no matter how you slice it, and no amount of helpful "filesystem not responding" notifications or suggestions to use FUSE/KIOslaves for everything are going to solve it.